While I'm building my own lineup for Silver League, I noticed that the duo of Gelatinous cube and Venari Seedsmith is very annoying due to high health combined with their passive ability that puts you in advantage as the battle progresses.
Combined with Lyanna GF (level 3) and Flesh Golem GF (level 4), this makes the combo even worse for your opponent.
Just add a tanky backline such as Earth elemental or Onyx Sentinnel then add some sneaky monsters. This combo will definitely have edge in high mana/long battles.

Core Cards:

▪️Summoner Lyanna Natura (Gold Foil, default level 3)
▪️Flesh Golem (level 3 to unlock Heal ability)
▪️Gelatinous Cube (level 1 will do but you can maxed it to level4)
▪️Venari Seedsmith (maxed it to level 3)

Advantage in battles:

▪️High sustainability
▪️Has some edge in speed
▪️Mylor Counter
▪️Good for Poison or earthquake rule set

Disadvantages:

▪️Mana Costly
▪️Can easily countered if no tanky backline
▪️50/50 chance on mage, adding mushroom will boost win oercentage against mage.

Below are some of the battles I won using this lineup.

P.S. There's no perfect lineup. The most effective strategy is to learn and understand key positioning and abilities. Scouting your opponent's past matches is also a key in winning battles.
This is just a guide or another lineup that will shock your opponent. :)

This is originally posted in my Facebook Page in Filipino language.